CN117581158A

CN117581158A - Multi-charged particle beam drawing device, multi-charged particle beam drawing method, and readable recording medium having program recorded thereon

Info

Publication number: CN117581158A
Application number: CN202280005325.1A
Authority: CN
Inventors: 野村春之
Original assignee: Nuflare Technology Inc
Current assignee: Nuflare Technology Inc
Priority date: 2022-04-26
Filing date: 2022-04-26
Publication date: 2024-02-20
Also published as: WO2023209825A1; JPWO2023209825A1; TW202343523A; US20240242931A1; KR20230153915A; JP7538240B2

Abstract

A multi-charged particle beam drawing apparatus according to an aspect of the present invention includes: a calculation processing unit configured to execute a calculation process of a rising temperature caused by heat generated by irradiation of a beam to each grid region in a processing region corresponding to a beam array region being supplied to a grid region of interest which is one of a plurality of grid regions, the calculation process being performed by a convolution process using the dose representative value of each grid region and a heat expansion function indicating heat expansion generated in the grid region; an effective temperature calculation unit that performs a repetitive process of repeating the calculation process while shifting the position of the processing region in the 2 nd direction on the bar-shaped region, and calculates, as effective temperatures of the grid region of interest, representative values of a plurality of the temperature rise rates obtained by performing the repetitive process a plurality of times until the grid region of interest is located from one end to the other end of the processing region in the 2 nd direction; and a dose correction unit configured to correct doses of a plurality of beams irradiating each of the grid regions of interest, using the effective temperature.

Description

Multi-charged particle beam drawing device, multi-charged particle beam drawing method, and readable recording medium having program recorded thereon

Technical Field

The present invention relates to a multi-charged particle beam drawing apparatus, a multi-charged particle beam drawing method, and a readable recording medium having a program recorded thereon, and for example, to a method for correcting resist heating (resistance heating) caused by multi-beam drawing.

Background

Photolithography, which is responsible for the progress of miniaturization of semiconductor devices, is an extremely important process for uniquely creating patterns in semiconductor manufacturing processes. In recent years, with the high integration of LSI, circuit line widths required for semiconductor devices have been miniaturized year by year. Here, electron beam (e-beam) drawing techniques have an essentially excellent resolution, and are used to draw a wafer or the like.

For example, there is a drawing device using multiple beams. By using multiple beams, a larger number of beams can be irradiated at a time than in the case of drawing with one electron beam, and the throughput can be greatly improved. In such a multi-beam type drawing apparatus, for example, electron beams emitted from an electron gun are passed through a mask having a plurality of holes to form multi-beams, blanking control is performed, and each of the non-blocked beams is reduced by an optical system, deflected by a deflector, and irradiated to a desired position on a sample.

Here, in the drawing using the electron beam, if irradiation energy is to be irradiated with the electron beam of higher density in a short time, there is a problem that a phenomenon called resist heating occurs as follows: the substrate temperature is overheated and the resist sensitivity is changed, and the line width accuracy is deteriorated. For example, in single beam drawing, a method of determining a dose correction amount of a current shot by accumulating the influence of a temperature rise of each past shot caused by one beam is adopted. However, in the multi-beam drawing, since a plurality of beams are used, the calculation amount becomes enormous in the method of accumulating the influence of the temperature rise per beam per emission in the past. In the multi-beam drawing, since a plurality of beams are emitted simultaneously, it is necessary to consider the influence of the temperature rise of the other plurality of beams from the wide area to be irradiated simultaneously.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2003-503837

Disclosure of Invention

Problems to be solved by the invention

An aspect of the present invention provides an apparatus and a method capable of correcting resist heating without accumulating the influence of temperature rise of each beam and each emission in multi-beam drawing.

Means for solving the problems

In one aspect of the present invention, a multi-charged particle beam drawing apparatus irradiates a drawing area on a sample surface with a multi-charged particle beam, the apparatus comprising:

a dividing unit configured to divide the drawing region into a plurality of grid regions in a 1 st direction and a 2 nd direction, which are a moving direction of a stage along each of the plurality of bar regions, in each of the plurality of bar regions divided in the 1 st direction by a 1 st direction dimension of a beam array region of the plurality of charged particle beams on the sample surface;

a dose representative value calculation unit that calculates, for each of the divided grid regions, representative values of a plurality of doses generated by irradiating a plurality of beams within the grid region as dose representative values;

a calculation processing unit configured to execute a calculation process of a rise temperature caused by heat generated by irradiation of a beam to each of the grid regions in the processing region corresponding to the beam array region being supplied to a grid region of interest which is one of the plurality of grid regions, the calculation process being performed by a convolution process using the dose representative value of each of the grid regions and a thermal expansion function indicating thermal expansion generated in the grid region;

An effective temperature calculation unit that performs a repetitive process of repeating the calculation process while shifting the position of the processing region in the 2 nd direction in the bar-shaped region, and calculates, as effective temperatures of the grid region of interest, representative values of a plurality of the temperature rise rates obtained by performing the repetitive process a plurality of times until the grid region of interest is located from one end to the other end of the processing region in the 2 nd direction;

a dose correction unit configured to correct doses of a plurality of beams irradiating each of the grid regions of interest, using the effective temperature; and

and a drawing means for drawing a pattern on the sample using the corrected doses of the multi-charged particle beam.

In one embodiment of the present invention, a multi-charged particle beam drawing method is characterized in that,

dividing a drawing region of a sample into a plurality of grid regions in a 1 st direction and a 2 nd direction which are moving directions of a stage along each of the plurality of bar regions in each of the plurality of bar regions divided in the 1 st direction by a 1 st direction dimension of a beam array region of a plurality of charged particle beams on a sample surface,

For each divided grid region, calculating a statistical value of a plurality of doses generated by irradiating a plurality of beams within the grid region as a dose statistical value,

performing a calculation process of calculating a rise temperature caused by the irradiation of the beam to each of the grid regions in the processing region corresponding to the beam array region, the calculation process being a convolution process using the dose statistic value for each of the grid regions and a heat expansion function indicating heat expansion generated in the grid region,

performing a repeating process of repeating the calculating process while shifting positions in the 2 nd direction in the bar-shaped region, calculating effective temperatures of the grid region of interest, which are representative values of a plurality of rising temperatures obtained by performing the repeating process a plurality of times until the grid region of interest is located from one end to the other end of the processing region in the 2 nd direction,

correcting a dose of a plurality of beams irradiating each of the grid regions of interest using the effective temperature,

a pattern is drawn on the sample using the multi-charged particle beams of the respective corrected doses.

A readable recording medium of an aspect of the present invention, on which a program is recorded, is configured to cause a computer to execute the steps of:

dividing a drawing region of a sample into a plurality of grid regions in a 1 st direction and a 2 nd direction which are moving directions of a stage along each of a plurality of stripe regions in each of the stripe regions divided in the 1 st direction by a 1 st direction dimension of a beam array region of a plurality of charged particle beams on a sample surface;

a step of calculating, for each divided grid region, a statistical value of a plurality of doses generated by irradiating a plurality of beams within the grid region as a dose statistical value;

a step of performing calculation processing for calculating an upward temperature increase caused by irradiation of a beam to each of the grid regions in a processing region corresponding to the beam array region, the calculation processing being performed by a convolution process using the dose statistic value for each of the grid regions and a thermal expansion function indicating thermal expansion generated in the grid region, the calculation processing being performed by supplying heat generated by irradiation of a beam to a grid region of interest which is one of the plurality of grid regions;

performing a repeating process of repeating the calculating process while shifting positions in the 2 nd direction in the bar-shaped region, and calculating effective temperatures of the grid region of interest, which are representative values of a plurality of raised temperatures obtained by performing the repeating process a plurality of times until the grid region of interest is located from one end to the other end of the 2 nd direction in the processing region; and

And correcting a dose of the plurality of beams irradiating each of the grid regions of interest using the effective temperature.

Effects of the invention

According to an aspect of the present invention, in the multi-beam drawing, the resist heating can be corrected without accumulating the influence of the temperature rise of each beam and each emission.

Drawings

Fig. 1 is a conceptual diagram showing the configuration of the drawing device according to embodiment 1.

Fig. 2 is a conceptual diagram showing the structure of the molded aperture array substrate according to embodiment 1.

Fig. 3 is a cross-sectional view showing the configuration of a blanking aperture array mechanism according to embodiment 1.

Fig. 4 is a schematic top view showing a part of the configuration in the membrane area of the blanking aperture array mechanism of embodiment 1.

Fig. 5 is a diagram showing an example of the separate blanking mechanism according to embodiment 1.

Fig. 6 is a conceptual diagram for explaining an example of the drawing operation of embodiment 1.

Fig. 7 is a diagram showing an example of a multi-beam irradiation region and a drawing target pixel according to embodiment 1.

Fig. 8 is a diagram for explaining an example of the multi-beam drawing operation in embodiment 1.

Fig. 9 is a diagram showing an example of a relationship between temperature distribution and temperature caused by irradiation of one beam to a region of 1 beam pitch amount in the comparative example of embodiment 1.

Fig. 10 is a diagram showing an example of a relationship between temperature distribution and temperature caused by simultaneous irradiation of multiple beams in embodiment 1.

Fig. 11 is a flowchart showing an example of the main part process of the drawing method of embodiment 1.

Fig. 12 is a diagram showing an example of the processing grid according to embodiment 1.

Fig. 13 is a diagram for explaining a method of calculating an effective temperature according to embodiment 1.

Fig. 14 is a diagram for explaining a part of the calculation formula of the effective temperature in embodiment 1.

Fig. 15 is a diagram for explaining an example of the calculation formula of the thermal expansion function according to embodiment 1.

Fig. 16 is a diagram for explaining another part of the calculation formula of the effective temperature in embodiment 1.

Fig. 17 is a diagram for explaining another part of the calculation formula of the effective temperature in embodiment 1.

Fig. 18 is a diagram for explaining another part of the calculation formula of the effective temperature in embodiment 1.

Fig. 19 is a diagram showing an example of the relationship between the line width CD and the temperature in embodiment 1.

Fig. 20 is a diagram showing an example of the relationship between the line width CD and the dose in embodiment 1.

Fig. 21 is a diagram for explaining a table speed profile according to embodiment 2.

Fig. 22 is a diagram for explaining an example of the calculation formula of the thermal expansion function according to embodiment 2.

Detailed Description

In the following, a configuration using an electron beam will be described as an example of a charged particle beam. However, the charged particle beam is not limited to an electron beam, and may be a beam using charged particles such as an ion beam.

Embodiment 1

Fig. 1 is a conceptual diagram showing the configuration of the drawing device according to embodiment 1. In fig. 1, the drawing device 100 includes a drawing mechanism 150 and a control system circuit 160. The drawing device 100 is an example of a multi-charged particle beam drawing device, and is an example of a multi-charged particle beam exposure device. The drawing mechanism 150 includes an electron column 102 (electron beam column) and a drawing chamber 103. An electron gun 201, an illumination lens 202, a shaped aperture array substrate 203, a blanking aperture array mechanism 204, a reduction lens 205, a limiting aperture substrate 206, an objective lens 207, a main deflector 208, and a sub deflector 209 are arranged in the electron column 102. An XY stage 105 is disposed in the drawing chamber 103. The XY stage 105 is provided with a sample 101 such as a mask for a substrate to be drawn at the time of drawing (at the time of exposure). The sample 101 includes an exposure mask for manufacturing a semiconductor device, a semiconductor substrate (silicon wafer) for manufacturing a semiconductor device, and the like. Further, a resist was coated on the sample 101. The sample 101 includes, for example, a mask blank coated with a resist, which has not been drawn. The XY stage 105 is further provided with a mirror 210 for measuring the position of the XY stage 105.

The control system circuit 160 includes storage devices 140, 142, 144 for controlling the computer 110, the memory 112, the deflection control circuit 130, digital-to-analog converter (DAC) amplifier units 132, 134, the lens control circuit 136, the stage control mechanism 138, the stage position measuring device 139, and the disk device. The control computer 110, the memory 112, the deflection control circuit 130, the lens control circuit 136, the stage control mechanism 138, the stage position measuring device 139, and the storage devices 140, 142, 144 are connected to each other via a bus not shown. DAC amplifier units 132 and 134 and a blanking aperture array mechanism 204 are connected to the deflection control circuit 130. The sub-deflector 209 is composed of electrodes of 4 poles or more, and each electrode is controlled by the deflection control circuit 130 via each DAC amplifier 132. The main deflector 208 is composed of electrodes of 4 poles or more, and each electrode is controlled by the deflection control circuit 130 via each DAC amplifier 134. The stage position measuring device 139 receives the reflected light from the mirror 210, and thereby measures the position of the XY stage 105 by using the principle of the laser interferometry.

The pattern density calculating unit 50, the dose calculating unit 52, the dividing unit 53, the dose representative value calculating unit 54, the tracking cycle time calculating unit 56, the convolution calculating unit 57, the effective temperature calculating unit 58, the modulation rate calculating unit 60, the correcting unit 62, the irradiation time data generating unit 72, the data processing unit 74, the transmission control unit 79, and the drawing control unit 80 are arranged in the control computer 110. The pattern density calculating unit 50, the dose calculating unit 52, the dividing unit 53, the dose representative value calculating unit 54, the tracking cycle time calculating unit 56, the convolution processing unit 57, the effective temperature calculating unit 58, the modulation rate calculating unit 60, the correcting unit 62, the irradiation time data generating unit 72, the data processing unit 74, the transfer control unit 79, and the drawing control unit 80 each include a processing circuit. Such a processing circuit includes, for example, a circuit, a computer, a processor, a circuit substrate, a quantum circuit, or a semiconductor device. The "parts" may use a common processing circuit (the same processing circuit), or may use different processing circuits (different processing circuits). The information input and output from and during the computation of the pattern density calculating unit 50, the dose calculating unit 52, the dividing unit 53, the dose representative value calculating unit 54, the tracking cycle time calculating unit 56, the convolution processing unit 57, the effective temperature calculating unit 58, the modulation rate calculating unit 60, the correcting unit 62, the irradiation time data generating unit 72, the data processing unit 74, the transmission control unit 79, and the drawing control unit 80 are stored in the memory 112 each time.

The drawing operation of the drawing device 100 is controlled by the drawing control unit 80. The transmission process of the irradiation time data of each emission to the deflection control circuit 130 is controlled by the transmission control section 79.

Further, chip data is input from the outside of the drawing device 100 and stored in the storage device 140. The drawing data includes chip data and drawing condition data. In the chip data, for example, a graphics code, coordinates, a size, and the like are defined for each graphics pattern. The drawing condition data includes information indicating how severe the drawing condition data is and a table speed.

The storage device 144 stores data on the modulation rate for calculating the correction of the resist heating, which will be described later.

Here, fig. 1 illustrates a configuration required for explaining embodiment 1. The drawing device 100 may generally have other configurations as needed.

Fig. 2 is a conceptual diagram showing the structure of the molded aperture array substrate according to embodiment 1. In fig. 2, holes (openings) 22 are formed in a matrix at a predetermined arrangement pitch in the shaped aperture array substrate 203 in p columns in the vertical (y direction) x q columns in the horizontal (x direction) (p, q. Gtoreq.2). In the example of fig. 2, for example, the case where 500 columns×500 rows of holes 22 are formed in the horizontal and vertical directions (x, y directions) is shown. The number of holes 22 is not limited thereto. Each hole 22 is formed in a rectangular shape of the same size and shape. Alternatively, the same diameter may be circular. A portion of the electron beam 200 passes through these multiple apertures 22, respectively, thereby forming multiple beams 20. In other words, the shaped aperture array substrate 203 forms the multiple beams 20.

Fig. 4 is a schematic top view showing a part of the configuration in the membrane area of the blanking aperture array mechanism of embodiment 1. In fig. 3 and 4, the positional relationship among the control electrode 24, the counter electrode 26, the control circuit 41, and the pad 343 is not shown uniformly. As shown in fig. 3, the blanking aperture array mechanism 204 includes a blanking aperture array substrate 31 using a semiconductor substrate made of silicon or the like, disposed on a support base 33. In the diaphragm region 330 in the central portion of the blanking aperture array substrate 31, a pass-through hole 25 (opening) through which each of the multiple beams 20 passes is opened at a position corresponding to each of the holes 22 of the shaped aperture array substrate 203 shown in fig. 2. In each of the plurality of through holes 25, a group (blanking device: blanking deflector) of the control electrode 24 and the counter electrode 26 is arranged at a position facing each other across the through hole 25. A control circuit 41 (logic circuit; unit) for applying a deflection voltage to the control electrode 24 for each through hole 25 is disposed in the blanking aperture array substrate 31 in the vicinity of each through hole 25. The opposing electrode 26 for each beam is grounded.

As shown in fig. 4, each control circuit 41 is connected to n-bit (e.g., 10-bit) parallel wiring for control signals. Each control circuit 41 is connected to a clock signal, a read signal, a transmission signal, a power supply wiring, and the like, in addition to the n-bit parallel wiring for the irradiation time control signal (data). These wirings and the like may be also used as wirings along a part of the parallel wirings. For each of the beams constituting the multi-beam 20, an individual blanking mechanism 47 is constituted by the control electrode 24, the counter electrode 26, and the control circuit 41. In embodiment 1, a shift register system is used as a data transfer system, for example. In the shift register system, the multiple beams 20 are divided into a plurality of groups for each of the multiple beams, and a plurality of shift registers for the multiple beams in the same group are connected in series. Specifically, the plurality of control circuits 41 formed in an array in the diaphragm region 330 are grouped at a predetermined pitch in the same row or the same column, for example. As shown in fig. 4, the groups of control circuits 41 in the same group are connected in series. Further, a signal from the pad 343 arranged for each group is transmitted to the control circuit 41 within the group.

Fig. 5 is a diagram showing an example of the separate blanking mechanism according to embodiment 1. In fig. 5, an amplifier 46 (an example of a switching circuit) is disposed in the control circuit 41. In the example of fig. 5, as an example of the amplifier 46, a CMOS (Complementary MOS) inverter circuit serving as a switching circuit is arranged. Either one of an L (low) potential (for example, a ground potential) lower than a threshold voltage and an H (high) potential (for example, 1.5V) higher than the threshold voltage is applied as a control signal to an Input (IN) of the CMOS inverter circuit. IN embodiment 1, the Output (OUT) of the CMOS inverter circuit applied to the control circuit 41 is set to a positive potential (Vdd) IN a state where an L potential is applied to the Input (IN) of the CMOS inverter circuit, and the corresponding beam 20 is deflected by an electric field generated by a potential difference from the ground potential of the counter electrode 26 and blocked by the limiting aperture substrate 206, thereby controlling the beam cut-off. On the other hand, IN a state (active state) IN which an H potential is applied to the Input (IN) of the CMOS inverter circuit, the Output (OUT) of the CMOS inverter circuit becomes the ground potential, and the potential difference from the ground potential of the counter electrode 26 disappears without deflecting the corresponding beam 20, and therefore, the aperture substrate 206 is restricted, thereby controlling the beam on. The blanking control is performed by this deflection.

Then, each individual blanking mechanism 47 individually controls the irradiation time of the emission for each beam using a counter circuit, not shown, in accordance with the irradiation time control signal transmitted for each beam.

Next, a specific example of the operation of the drawing mechanism 150 will be described. An electron beam 200 emitted from an electron gun 201 (emission source) illuminates the entire shaped aperture array substrate 203 substantially vertically through an illumination lens 202. A plurality of rectangular holes 22 (openings) are formed in the shaped aperture array substrate 203, and the electron beam 200 illuminates a region including all of the plurality of holes 22. Each part of the electron beam 200 irradiated to the positions of the plurality of holes 22 passes through the plurality of holes 22 of the shaped aperture array substrate 203, thereby forming, for example, a multi-beam (a plurality of electron beams) 20 having a rectangular shape. Such multiple beams 20 pass through blankers (1 st deflector: individual blanking mechanism 47) respectively corresponding to the blanking aperture array mechanism 204. Such a blanking device performs blanking control of the beam passing alone so as to turn on the beam for a set drawing time (irradiation time).

The multibeam 20 having passed through the blanking aperture array mechanism 204 is reduced by the reduction lens 205, and travels toward a hole formed in the center of the limiting aperture substrate 206. Here, the position of the electron beam deflected by the blanker of the blanking aperture array mechanism 204 is deviated from the hole in the center of the limiting aperture substrate 206 and is blocked by the limiting aperture substrate 206. On the other hand, the electron beam that is not deflected by the blanker of the blanker aperture array mechanism 204 passes through the aperture that restricts the center of the aperture substrate 206 as shown in fig. 1. In this way, the limiting aperture substrate 206 shields each beam deflected by the individual blanking mechanism 47 into a beam-off state. Then, each beam of 1 emission is formed by using the beam having passed through the limiting aperture substrate 206, which is formed from the time when the beam is turned on to the time when the beam is turned off. The multiple beams 20 passing through the limiting aperture substrate 206 are focused by the objective lens 207 to form a pattern image of a desired reduction ratio, and the entire multiple beams 20 passing through the limiting aperture substrate 206 are deflected in the same direction by the main deflector 208 and the sub deflector 209 at the same time, so that the irradiation positions on the sample 101 of each beam are irradiated. For example, when the XY table 105 continuously moves, the main deflector 208 deflects the multiple beams 20 so that the irradiation positions of the beams follow the movement of the XY table 105, thereby performing tracking control. The multiple beams 20 irradiated at a time are desirably arranged at a pitch obtained by multiplying the arrangement pitch of the plurality of holes 22 of the shaped aperture array substrate 203 by the above-described desired reduction ratio.

Fig. 6 is a conceptual diagram for explaining an example of the drawing operation of embodiment 1. As shown in fig. 6, the drawing region 30 of the sample 101 is virtually divided into a plurality of strip-shaped regions 32 in a long strip shape with a predetermined width in the y direction, for example. First, the XY stage 105 is moved so that the irradiation region 34 which can be irradiated by one irradiation of the multiple beams 20 is positioned at the left end of the 1 st bar region 32 or at a position further to the left, and drawing is started. When drawing the 1 st bar area 32, the XY table 105 is moved in, for example, the-x direction, and drawing is performed relatively in the x direction. The XY stage 105 continuously moves, for example, at a constant speed. After the drawing of the 1 st bar area 32 is completed, the stage position is moved in the-y direction, and the XY stage 105 is moved in the x direction, for example, so that the drawing is performed in the-x direction. By repeating such an operation, each bar region 32 is sequentially drawn. By drawing while alternately changing the orientation, the drawing time can be shortened. However, the drawing is not limited to the case where the orientation is alternately changed while drawing, and the drawing may be performed in the same direction when drawing each bar region 32. In the case of moving the XY table 105 at a constant speed, the continuous movement speed may be different for each bar. In one shot, a plurality of shot patterns equal in number to each hole 22 are formed at a maximum at one shot by using a plurality of beams formed by shaping each hole 22 of the aperture array substrate 203.

Fig. 7 is a diagram showing an example of a multi-beam irradiation region and a drawing target pixel according to embodiment 1. In fig. 7, the stripe region 32 is divided into a plurality of grid regions in a grid shape, for example, in the beam size of the multi-beam 20. Each of the mesh regions is a pixel 36 (unit irradiation region, irradiation position, or drawing position) to be drawn. The size of the pixel 36 to be drawn is not limited to the beam size, and may be any size regardless of the beam size. For example, the beam may be formed of a beam size of 1/a (a is an integer of 1 or more). Fig. 7 illustrates an example in which the drawing region 30 of the sample 101 is divided into a plurality of stripe regions 32 in the y direction by a width dimension substantially equal to the dimension of the irradiation region 34 (beam array region) that can be irradiated by the irradiation of the multi-beam 20 at one time, for example. The size of the rectangular irradiation region 34 in the x-direction can be defined by the number of beams in the x-direction x the inter-beam distance in the x-direction. The dimension of the rectangular irradiation region 34 in the y direction can be defined by the number of beams in the y direction x the inter-beam distance in the y direction. In the example of fig. 7, for example, illustration of 500 columns×500 rows of multibeams is omitted for 8 columns×8 rows of multibeams. A plurality of pixels 28 (drawing positions of the beams) that can be irradiated by the single emission of the multi-beam 20 are shown in the irradiation region 34. The spacing between adjacent pixels 28 on the sample plane is the spacing between the beams of the multiple beams 20. A sub-irradiation region 29 (pitch unit) is formed by a rectangular region surrounded by the beam pitch in the x-and y-directions. Each sub-illuminated area 29 comprises one pixel 28. In the example of fig. 7, for example, a pixel at the upper left corner of each sub-irradiation region 29 is shown as a pixel 28 located at the drawing position of the beam. Each sub-irradiation region 29 is composed of, for example, 10×10 pixels. In the example of fig. 7, each sub-irradiation region 29 of 10×10 pixels is omitted from the illustration of 4×4 pixels, for example.

Fig. 8 is a diagram for explaining an example of the multi-beam drawing operation in embodiment 1. Fig. 8 illustrates an example in which the sub-irradiation regions 29 on the surface of the sample 101 are drawn by 10 different beams. In the example of fig. 8, a drawing operation is shown in which the XY stage 105 is continuously moved at a speed of, for example, a distance L of 25 beam pitch amounts while drawing a region of 1/10 (1 of the number of beams to be irradiated) in each sub-irradiation region 29. In the drawing operation shown in the example of fig. 8, for example, the XY stage 105 is shown to sequentially shift the irradiation position (pixel 36) by the sub-deflector 209 during the period of moving by the distance L of 25 beam pitch amounts at the emission cycle time t _trk-cycle The inner emission of 10 multiple beams 20 depicts (exposes) the case of different 10 pixels within the same sub-illuminated area 29. During such a period of drawing (exposing) 10 pixels, the entire multi-beam 20 is deflected by the main deflector 208, whereby the irradiation region 34 follows the movement of the XY stage 105, so that the irradiation region 34 is prevented from being displaced relative to the sample 101 by the movement of the XY stage 105. In other words, tracking control is performed. Therefore, in each tracking control, the distance L deflected by the main deflector 208 together is the tracking distance.

When the tracking cycle is finished, tracking reset is performed, and the last tracking start position is returned. Since the drawing of the 1 st pixel row from the top of each sub-irradiation region 29 is completed, after the tracking reset is performed, the sub-deflector 209 is first deflected so that the drawing position of the beam matches (is shifted) in the next tracking cycle, so that the pixel column of the 2 nd row, for example, which is not yet drawn, of each sub-irradiation region 29 is drawn. Thus, each time the tracking reset is performed, the pixel column to be described next is changed. During the 10 times tracking control, each pixel 36 in each sub-irradiation region 29 is depicted once. In drawing the bar-shaped region 32, by repeating such operations, as shown in fig. 6, the positions of the irradiation regions 34 are sequentially moved in accordance with the irradiation regions 34a to 34o, and the drawing of the bar-shaped region 32 is performed.

In the example of fig. 8, the sub-irradiation region 29 located on the sample surface at the lower right corner of the irradiation region 34 of the width W is moved by the distance L from the lower right corner of the irradiation region 34 in the left direction in the 2 nd tracking control. Therefore, the sub-irradiation region 29 located at the lower right corner of the irradiation region 34 in the 1 st tracking control is depicted by another beam at a position separated by the distance L in the left direction from the lower right corner of the irradiation region 34 in the 2 nd tracking control. Here, the drawing is performed by beams separated from the beam at the lower right corner toward the-x direction by, for example, 25 beams.

For example, in the drawing process in which the path of each stage 1 is set to be multiple 2, each pixel 36 in each sub-irradiation region 29 can be drawn twice by tracking control for 20 times.

Fig. 9 is a diagram showing an example of a relationship between temperature distribution and temperature caused by irradiation of one beam to a region of 1 beam pitch amount in the comparative example of embodiment 1. In fig. 9, the vertical axis represents temperature, and the horizontal axis represents temperature distribution. As shown in fig. 9, the mountain area of the temperature distribution caused by irradiation of one beam is wide. Thus, the wide range is affected. However, as an influence on the mountain area, the temperature rise by one beam is as small as 0.01 ℃ or less.

Fig. 10 is a diagram showing an example of a relationship between temperature distribution and temperature caused by simultaneous irradiation of multiple beams in embodiment 1. In fig. 10, the vertical axis represents temperature, and the horizontal axis represents temperature distribution. The temperature rise by one beam is at most 0.01 ℃ or less, but when 500×500=25 ten thousand beams are irradiated simultaneously, for example, the temperature rises by the beams overlap in the mountain area as shown in fig. 10. As a result, for example, when 500×500=25 ten thousand beams are simultaneously irradiated, a significant temperature rise occurs in the mountain area.

Techniques related to heating effect prediction and correction in single beam-based 1-beam drawing are known, but there is no precedent for heating effect correction in a multi-beam drawing method in which a plurality of beams, for example, 25 ten thousand are simultaneously emitted several times per stage path. The calculation of the heat generated by, for example, 25 ten thousand individual beams like a single beam is not realistic from the calculation point of view.

In the multibeam, the current density J is extremely small compared to a single beam such as the VSB mode, and thus the temperature slowly rises. And, the temperature distribution due to 1 emission during this period is diffused by several tens μm. Therefore, even if the emission data and the dose data in the bar shape are divided and calculated together to some extent, sufficient accuracy can be obtained. In addition, as described above, in the multi-beam drawing, the raster scanning system is used, and therefore, the position is determined according to time. Therefore, if the dose data and the drawing speed (table speed or tracking cycle time) are determined, the rising temperature is determined. A simpler correction can be made than the depiction of VSB modes requiring both position and time.

Therefore, in embodiment 1, the dose information of the bar-shaped region 32 is assigned to certain m×n pieces of pixel information including the grid of interest for which the temperature should be found. The temperature at which the beam is irradiated is calculated for each of a plurality of times by taking as input dose information before and after the region and parameters for determining the progress speed of the drawing such as the tracking cycle time. The statistics (e.g., average) are then used for correction as effective temperatures. Hereinafter, specific description will be made.

Fig. 11 is a flowchart showing an example of the main part process of the drawing method of embodiment 1. In fig. 11, the drawing method of embodiment 1 performs a series of steps including a pattern density calculation step (S102), a dose calculation step (S104), a processing grid division step (S106), a tracking cycle time calculation step (S108), a dose representative value calculation step (S110), a convolution calculation processing step (S111), an effective temperature calculation step (S112), a modulation rate calculation step (S114), a correction step (S118), an irradiation time data generation step (S120), a data processing step (S122), and a drawing step (S124).

First, the drawing data is read out from the storage device 140 for each bar area 32.

As a pattern density calculating step (S102), the pattern density calculating unit 50 calculates a pattern density ρ (pattern area density) for each pixel 36 in the target stripe region 32. The pattern density calculating unit 50 creates a pattern density map using the calculated pattern density ρ of each pixel 36 for each stripe region 32. The pattern density of each pixel 36 is defined as each element of the pattern density map. The created pattern density map is stored in the memory 144.

As a dose calculation step (S104), the dose calculation unit 52 calculates, for each pixel 36, a dose (irradiation amount) to be irradiated to the pixel 36. For example, the dose may be calculated as a value obtained by multiplying the preset reference irradiation amount Dbase by the proximity effect correction irradiation coefficient Dp and the pattern density ρ. In this way, the preferred dose is obtained in proportion to the area density of the pattern calculated for each pixel 36. The drawing region (here, for example, the bar region 32) is virtually divided into a plurality of adjacent grid regions (grid regions for calculating the proximity effect correction) in a grid shape with a predetermined size with respect to the proximity effect correction irradiation coefficient Dp. The size of the adjacent mesh region is preferably set to about 1/10 of the influence range of the proximity effect, for example, about 1 μm. Then, the drawing data is read from the storage device 140, and the pattern area density ρ' of the pattern disposed in the adjacent mesh region is calculated for each adjacent mesh region.

Next, for each neighboring grid region, a neighboring effect correction irradiation coefficient Dp for correcting a neighboring effect is calculated. Here, the size of the grid region for calculating the proximity effect correction irradiation coefficient Dp does not need to be the same as the size of the grid region for calculating the pattern area density ρ'. The correction model and the calculation method of the proximity effect correction irradiation factor Dp may be the same as those used in the conventional single beam drawing method.

Then, the dose calculation unit 52 creates a dose map (1) using the calculated dose for each pixel 36 for each bar-shaped region 32. The dose of each pixel 36 is defined as each element of the dose map (1). In the above example, the case where the dose is calculated as the absolute value multiplied by the reference irradiation amount Dbase is shown, but the present invention is not limited thereto. The dose may be calculated as a relative value to the reference dose Dbase assuming that the reference dose Dbase is 1. In other words, the dose may be calculated as a coefficient value obtained by multiplying the proximity effect correction irradiation coefficient Dp and the pattern density ρ. The produced dose map (1) is stored in the storage means 144.

As a processing grid dividing step (S106), the dividing unit 53 (dividing processing circuit) divides the drawing region of the sample into a plurality of grid regions in the y direction and in the x direction (2 nd direction) which is the moving direction of the stage along each of the plurality of bar regions in each of the plurality of bar regions divided in the y direction by the size of the beam array region of the multi-charged particle beam on the sample surface in the y direction (1 st direction). Specifically, the dividing unit 53 (dividing processing circuit) divides each of the strip regions 32 into a plurality of processing grids (grid regions) in the y direction (1 st direction) and the x direction (2 nd direction) orthogonal to the y direction by a size of 1/N (N is an integer of 2 or more) of the beam array region.

Fig. 12 is a diagram showing an example of the processing grid according to embodiment 1. As described above, the drawing region 30 of the sample 101 is divided into the plurality of stripe regions 32 in the y direction, for example, by the dimension W of the irradiation region 34 (beam array region) of the multi-beam 20 on the surface of the sample 101. Each stripe region 32 is divided into a plurality of processing grids (grid regions) 39 by a dimension of 1/N (N is an integer of 2 or more) of the dimension W of the irradiation region 34 (beam array region). The dimension s of each processing grid 39 is formed by a dimension larger than the sub-irradiation region 29 of the beam pitch dimension.

In embodiment 1, the size s of the processing grid 39 is preferably set to the tracking distance L, for example. The tracking distance L is k times the size of the inter-beam space on the surface of the sample 101 (k is a natural number). The tracking distance L is set to, for example, 25 times the inter-beam spacing dimension in the above example. Therefore, the dimension s of the processing grid 39 is preferably set to a dimension of 25 beam pitch amounts, for example. Thus, the dimension s of the processing grid 39 is a dimension larger than the inter-beam spacing dimension on the surface of the sample 101. The processing grid 39 is a region sufficiently large for the pixels 36 that are a unit region for irradiating each beam.

As the tracking cycle time calculation step (S108), the tracking cycle time calculation unit 56 calculates the tracking cycle time t _trk-cycle . Tracking cycle time t _trk-cycle As shown in the following equation (1), the tracking distance L can be obtained by dividing the table velocity v. Here, the speed v in the case where the XY table 105 moves at a constant speed in drawing of the bar-shaped region 32 is used. In addition, since the size s=l of the processing grid 39, the cycle time t is tracked as shown in the following equation (1-1) _trk-cycle The dimension s of the processing grid 39 can be obtained by dividing it by the table speed v. In addition, the dimension s of the processing grid 39 is 1/N of the width W of the beam array region, i.e. the width of the stripe region 32, and therefore the tracking cycle time t _trk-cycle As shown in the following equation (1-1), the beam array area width W can be obtained by dividing 1/N by the stage velocity v.

[ number 1 ]

(1-1)t _trk-cycle ＝L/v＝s/v＝(W/N)/v

As a dose representative value calculating step (S110), the dose representative value calculating unit 54 (dose statistic calculating circuit) calculates, for each divided processing grid 39, a representative value based on a plurality of doses irradiating a plurality of beams within the processing grid 39 as a dose representative value D. A plurality of sub-illuminated areas 29 are contained within the processing grid 39. As described above, each sub-irradiation region 29 is irradiated with a plurality of different beams. In the above example, for example, a plurality of pixels 36 are included within the processing grid 39 illuminated by 10 different beams separated by 25 beam spacing in the x-direction. Here, a representative value of the dose (dose representative value Dij) defined in all the pixels 36 within the processing grid 39 is calculated. The representative value may be, for example, an average value, a maximum value, a minimum value, or a central value. Here, as the dose representative value Dij, for example, an average value, that is, an average dose is calculated. The dose representative value calculation unit 54 creates a dose representative value map using the calculated dose representative values Dij of the respective processing grids 39. The dose of each processing grid 39 is defined as each element of the dose representative value map. i denotes an index in the x-direction of the processing grid 39. j represents the index in the y-direction of the processing grid 39. The produced dose representative value map is stored in the memory 144.

As the convolution calculation processing step (S111), the convolution calculation processing unit 57 performs calculation processing of the rising temperature caused by the heat generated by irradiation of the beam to each processing grid 39 in the processing region corresponding to the beam array region being supplied to the attention grid region which is one of the plurality of processing grids 39. This calculation process is performed by a convolution process using the dose representative value of each processing grid 39 and a thermal expansion function representing thermal expansion generated by the processing grid 39.

As the effective temperature calculating step (S112), the effective temperature calculating unit 58 (effective temperature calculating circuit) performs the repetitive processing of repeating the above-described calculation processing while shifting the position of the processing region corresponding to the beam array region in the x-direction on the bar-shaped region, and calculates, as the effective temperature of the grid region of interest, representative values of a plurality of upward temperatures obtained by performing such repetitive processing a plurality of times until the processing grid 39 reaches the position from one end to the other end of the processing region in the x-direction. Specifically, the effective temperature calculation unit 58 (effective temperature calculation circuit) calculates the effective temperature for each processing grid 39 using the dose statistic Dij for each processing grid 39 and the thermal expansion function PSF indicating the thermal expansion generated in each grid. The thermal expansion function PSF can be defined by the following equation (1-2), for example, as a general thermal expansion equation.

[ number 2 ]

A function representing the surface temperature of the quartz glass substrate obtained from the expression (1-2) can be used. Here, λ represents the thermal diffusivity of the substance that diffuses at temperature. An example of the solution of the above formula is described below as formula (3-1).

While shifting the rectangular region in the x direction by the size s of the processing grid 39 on the bar region 32 of the object, a process of performing convolution processing of increasing the temperature by applying heat generated by irradiating beams to each processing grid 39 in the rectangular region, which is the processing region having the same size as the beam array region composed of n×n processing grids 39, using the dose statistic Dij and the thermal spread function PSF calculation is performed until the target grid region is included in the rectangular region. The effective temperature calculation unit 58 performs such processing N times from the position of one end of the rectangular region in the x direction of the grid region of interest to the position of the other end. Then, the effective temperature calculating section 58 calculates a statistical value of the result of the convolution processing of such N times as an effective temperature T (k, l).

Fig. 13 is a diagram for explaining a method of calculating an effective temperature according to embodiment 1. The effective temperature T (k, l) can be defined by the formula (2) shown in fig. 13. In the bar-shaped region 32, M processing grids 39 are arranged in the x-direction, and N processing grids 39 are arranged in the y-direction. In equation (2), the processing grid 39 of the first row in the y-direction and the k-th column in the x-direction among the plurality of processing grids 39 in the bar region 32 is expressed as a grid region of interest.

In equation (2), i represents an index in the x direction in the dose statistic map. The index i=0 in the x-direction of the processing grid 39 defined as the left end of the bar area 32.

j represents the index in the y-direction in the dose statistics map. The index j=0 in the y-direction of the processing grid 39 defined as the lowermost portion of the bar area 32.

N represents the grid number in the longitudinal direction (y-direction) of the input dose map for effective temperature calculation.

M represents the number of grids in the lateral direction (x-direction) of the input dose map for effective temperature calculation.

(k, l) represents an index (reference number) of a processing grid (a grid region of interest) that calculates an effective temperature T within (m×n) processing grids.

Dij: representing the dose statistics of the processing grid 39 assigned to the index (k, l) in the dose statistics map. (μC/cm 2)

m represents the first-n+1 to/tracking reset numbers performed before the beam array region (n×n) passes through the grid of interest (k, l). When m=l-n+1, the grid of interest is located at the right end of the beam array region of (n×n). When m=l, the grid of interest is located at the left end.

n represents the 0 th to m th tracking reset numbers.

The 1 st tracking control (tracking cycle) has not yet performed tracking reset, and therefore the tracking reset number is zero. The tracking control of the 2 nd time performs tracking reset of 1 time, and thus the tracking reset number is 1.

PSF (n, m, k-i, l-j) represents a thermal expansion function.

Fig. 14 is a diagram for explaining a part of the calculation formula of the effective temperature in embodiment 1. In fig. 14, a portion surrounded by a broken line in the expression (2) represents a calculation portion of the convolution processing. In the calculation section of the convolution processing of the equation (2), convolution processing is performed to calculate the rising temperature caused by the heat generated by irradiating beams to each grid region within the rectangular region 35 of the same size as the beam array region constituted by the n×n processing grids 39 being supplied to the grid region of interest of the index (k, l). A rectangular region 35 having the left end of the rectangular region 35 as the N-th column of the processing grid 39 and the right end of the rectangular region 35 as the n+n-1-th column of the processing grid 39 is used. Accordingly, N processing grids 39 corresponding to the N-th column to the n+N-1-th column in the x-direction and the 0-th row to the N-1-th row in the y-direction are arranged in the rectangular region 35.

Fig. 15 is a diagram for explaining an example of the calculation formula of the thermal expansion function according to embodiment 1. The heat spreading function PSF (n, m, k-i, l-j) is defined by the formula (3-1) shown in FIG. 15. Based on the initial condition when the same heat is applied to the volume obtained by multiplying the grid size by Rg by the beam irradiation on the substrate surface, the above heat conduction equation is solved under the boundary condition that the XY direction is infinity and the Z direction is semi-infinity in the substrate depth direction, whereby equation (3-1) can be obtained.

The symbols repeated with the formula (2) in the heat spreading function PSF (n, m, k-i, l-j) represent the same symbols as the formula (2). The thermal spread function PSF (n, m, k-i, l-j) shown in fig. 15 defines a case where the XY table 105 moves at a constant speed in a direction opposite to, for example, the x direction (-x direction), which is the drawing direction. As shown in fig. 15, the heat spreading function PSF (n, m, k-i, l-j) is defined using a tracking cycle time obtained from the velocity v of the XY table 105.

In the formula (3-1), rg represents the range of the electron beam of 50kV in quartz. For example, the range Rg= (0.046/ρ) E is used ^1.75 。

ρ represents the density of the substrate (quartz) (e.g., 2.2g/cm 3).

σn, m represents a function determined by the number of tracking resets (m-n) from nth to mth. The function σn, m is defined as equation (3-3).

Function A is defined as equation (3-2).

In the formula (3-2), V represents an acceleration voltage of the electron beam.

Cp represents the specific heat of the substrate (quartz) (e.g., 0.77J/g/K).

In the formula (3-3), λ represents the thermal diffusivity of the substrate (quartz) (for example, 0.0081 cm. Times.2/sec).

(m-n) represents the number of tracking resets performed from the nth to the mth.

t _trk-cycle Indicating the tracking cycle time. Tracking cycle time t _trk-cycle Represented by the formula (3-4). The same as in formula (1).

v _stage Indicating the table velocity v.

In general, the multi-beam drawing apparatus optimizes the stage velocity v in the stage path _stage = (certain), the transmission ends in the time between tracks (10 transmissions in the previous example). Since the tracking distance L (=w/N) is followed at the table speed, the tracking cycle time t _trk-cycle Can be defined by formula (1-1).

Fig. 16 is a diagram for explaining another part of the calculation formula of the effective temperature in embodiment 1. For the convolution processing described in fig. 14, the convolution processing is performed while shifting the rectangular region 35 from the left end (n=0) of the bar region 32 by the size s of the processing grid 39 in the x direction until the grid region of interest of the index (k, l) is included in the rectangular region 35 (n=m). The calculation section surrounded by the broken line of the formula (2) shown in fig. 16 represents such processing. Fig. 16 illustrates an example in which the rectangular region 35 is moved until the grid region of interest serving as the index (k, l) is located at the right end of the rectangular region 35. In this state, the rectangular region 35 has its left end located in the kth-n+1 column and its right end located in the kth column.

Fig. 18 is a diagram for explaining another part of the calculation formula of the effective temperature in embodiment 1. In fig. 18, the processing performed by the calculation section of fig. 17 is specifically expressed by a formula.

As for the processing shown in fig. 16, as shown in fig. 17, N times of processing are performed from the position of one end, i.e., the right end, to the position of the other end, i.e., the left end, within the rectangular region 35 of the grid region of interest in the x direction. In other words, as shown in fig. 18, the processing shown in fig. 16 from n=0 to n=m=k-n+1, the processing shown in fig. 16 from n=0 to n=m=k-n+2, the processing shown in fig. 16 from n=0 to n=m=k-n+3, the processing … …, and the processing shown in fig. 16 from n=0 to n=m=k are performed, and the total of these processes is calculated. Since the rectangular region 35 has N processing grids 39 arranged in the x-direction, N times of processing are performed from the right end to the left end of the rectangular region 35 in the grid region of interest. The calculation section surrounded by the broken line of the formula (2) shown in fig. 17 represents such processing. Then, a statistical value of the result of the convolution processing of N times is calculated as the effective temperature T (k, l). The calculation section surrounded by the broken line of the formula (2) shown in fig. 18 represents such processing. In the example of the formula (2), an average value obtained by dividing the total of N times of convolution processing by N is calculated as the effective temperature T (k, l).

The number of divisions of the rectangular region and the number of calculation processes do not necessarily coincide. That is, the number of times of calculation processing (downsampling) may be smaller than N. Further, the number may be divided into N, and the N number may be allocated (up-sampled) to a larger number of grids than N.

The effective temperature T (k, l) is not limited to the average value, and may be a maximum value, a minimum value, or a central value of the results of the convolution processing of N times. More preferably a central value. Further preferably an average value.

The effective temperature T (i, j) is obtained for each position (i, j) of the processing grid 39 by changing the position of the grid region of interest.

As described above, in embodiment 1, instead of calculating the temperature rise per emission and per beam, the effective temperature T (i, j) in units of the processing grid 39 is calculated using the dose statistic Dij of the processing grid 39. The effective temperature T (i, j) can be calculated for each of the processing grids 39 that is sufficiently large compared to the pixels 36 that become the unit area irradiated with the beam of each emission. Therefore, the calculation amount can be greatly reduced.

As a modulation rate calculation step (S114), the modulation rate calculation unit 60 calculates a modulation rate α (x) of the dose depending on the effective temperature T.

Fig. 19 is a diagram showing an example of the relationship between the line width CD and the temperature in embodiment 1. In fig. 19, the vertical axis represents the line width CD (Critical Dimension), and the horizontal axis represents the temperature. As shown in fig. 19, it is seen that the variation in line width CD increases as the temperature of the resist increases. There is a linear relationship between CD variation ΔCD/ΔT [ nm/K ] based on the heating effect. This value varies depending on the type of resist and the type of substrate, and is obtained by performing experiments on these. Therefore, an approximation formula is obtained that approximates the CD variation Δcd per unit temperature Δt. Such related data (1) is inputted from the outside and stored in the storage 144.

Fig. 20 is a diagram showing an example of the relationship between the line width CD and the dose in embodiment 1. In fig. 20, the vertical axis represents the line width CD, and the horizontal axis represents the dose. In the example of fig. 20, the horizontal axis is represented using logarithms. As shown in fig. 20, the line width CD depends on the pattern density, and as the dose increases, the line width CD also increases. Experiments were performed to obtain the relationship Δcd/Δd between CD variation and dose depending on each resist, substrate type, and pattern density. Then, an approximation formula is obtained in which the CD variation Δcd per unit dose is approximated. Such related data (2) is inputted from the outside and stored in the storage 144.

The modulation factor calculation unit 60 reads the related data (1) and (2) from the storage 144, and calculates the dose change amount Δd per unit temperature Δt depending on the pattern density as the modulation factor α (x) of the dose depending on the effective temperature T. The modulation rate α (x) depending on the pattern density ρ is defined by the following equation (5).

(5)α(x)＝(ΔCD/ΔT)/(ΔCD/ΔD) _ρ ＝(ΔD/ΔT) _ρ

As a correction step (S118), the correction unit 62 (dose correction circuit) corrects the doses of the plurality of beams irradiating each grid region of interest using the effective temperature T (i, j). The correction amount can be obtained as a value obtained by multiplying the effective temperature T (i, j) by the modulation rate α (x). The corrected dose D' (x) can be obtained by the following equation (6). x denotes the index of the pixel 36. (i, j) represents an index of the processing grid. The pattern density ρ may be a pattern density of the target pixel 36.

(6)D′(x)＝D(x)-T(i，j)·α(x)

Then, the correction unit 62 creates a dose map (2) using the calculated corrected dose D' (x) for each pixel 36 for each bar region 32. The dose D' (x) of each pixel 36 is defined as each element of the dose map (2). From this, the corrected (modulated) dose distribution D' (x) is obtained. That is, the CD size of the temperature rise amount can be returned according to the design size. The produced dose map (2) is stored in the storage means 144.

As the irradiation time data generation step (S120), the irradiation time data generation unit 72 calculates, for each pixel 36, the irradiation time t of the electron beam for inputting the calculated corrected dose D' (x) to the pixel 36. The irradiation time t can be calculated by dividing the dose D' (x) by the current density J. When the dose D (x) before correction defined in the dose map (1) is a relative value (coefficient value of dose) with respect to the reference irradiation amount Dbase calculated assuming that the reference irradiation amount Dbase is 1, the dose statistic Dij of each processing grid 39 is also calculated as a relative value with respect to the reference irradiation amount Dbase. Therefore, the effective temperature T (i, j) of each processing grid 39 is also calculated as a relative value with respect to the reference irradiation amount Dbase. Therefore, in this case, the irradiation time t can be calculated by dividing the value obtained by multiplying the dose D' (x) by the reference irradiation amount Dbase by the current density J.

The irradiation time t of each pixel 36 is calculated as a value within the maximum irradiation time Ttr that can be irradiated by 1 emission of the multi-beam 20. The irradiation time t of each pixel 36 is converted into gradation value data in which the maximum irradiation time Ttr is set to, for example, 0 to 1023 gradation (10 bits) of 1023 gradation. The gradation-performed irradiation time data is stored in the storage device 142.

As the data processing step (S122), the data processing section 74 rearranges the irradiation time data in the drawing order in the emission order, and rearranges the irradiation time data in the data transfer order in consideration of the arrangement order of the shift registers of the respective groups.

As the drawing step (S124), the transfer control unit 79 transfers the irradiation time data to the deflection control circuit 130 in the emission order under the control of the drawing control unit 80. The deflection control circuit 130 outputs a blanking control signal to the blanking aperture array mechanism 204 in the transmission order, and outputs deflection control signals to the DAC amplifier units 132, 134 in the transmission order. Then, the drawing means 150 draws a pattern on the sample 101 using the multiple beams 20 of the dose D' (x) corrected using the effective temperatures T (i, j).

In the above example, description has been made of the case where the drawing processing is sequentially performed on the bar-shaped region 32 in which the calculation of the end dose D' (x) is completed. For example, during the drawing process of a certain bar 32, the calculation of the dose D' (x) of the bar 32 preceding the bar 32 or the two bars 32 preceding the bar 32 in the drawing process is performed in parallel. In other words, the case where the calculation of the dose D' (x) is performed in parallel with the rendering process is described. However, the present invention is not limited thereto. As a pretreatment before the drawing process is started, the effective temperature T (i, j) and/or the dose D' (x) may be performed.

As described above, according to embodiment 1, in the multi-beam drawing, the resist heating can be corrected without accumulating the influence of the temperature rise per beam emitted per beam.

Embodiment 2

In embodiment 1, the case where the XY stage 105 is moved at a constant speed in the direction opposite to the drawing direction during drawing of the bar-shaped region 32 has been described, but the present invention is not limited thereto. In embodiment 2, a case where the XY table 105 is variable-speed-moved will be described. The configuration of the drawing device 100 of embodiment 2 is the same as that of fig. 1. The main part steps of the drawing method of embodiment 2 are the same as those of fig. 11. The following is the same as in embodiment 1 except for the points specifically described.

Fig. 21 is a diagram for explaining a table speed profile according to embodiment 2. Fig. 21 shows a case where the speed of the XY table 105 changes at predetermined intervals in the x direction. Information of such a speed profile is stored in the storage means 144. The speed profile may be calculated in the drawing device 100, or may be calculated outside the drawing device 100 and input to the drawing device 100. In the case of calculation in the drawing apparatus 100, a speed calculation unit, not shown, may be disposed in the control computer 110.

Fig. 22 is a diagram for explaining an example of the calculation formula of the thermal expansion function according to embodiment 2. The heat spreading function PSF (n, m, k-i, l-j) is defined by the formula (3-1) shown in FIG. 22. In FIG. 22, the formulas (3-1) and (3-2) are the same as in FIG. 15. The heat expansion function PSF (n, m, k-i, l-j) of embodiment 2 defines a case where the XY table 105 is variably moved in the opposite direction (-x direction) to, for example, the x direction, which is the drawing direction. As shown in fig. 22, the heat spreading function PSF (n, m, k-i, l-j) is defined using a tracking cycle time obtained from the velocity v of the XY table 105.

In the case where the XY table 105 is variable-speed-moved, the function σn, m is defined in equation (7-1). The tracking cycle time can be defined as a value obtained by dividing the tracking distance L (=w/N) by the table speed v. The size s of the processing grid 39 is set to the tracking distance L. Thus, the cycle time t is tracked ^p _trk-cycle Defined by formula (7-2).

v ^p _stage Representation variableA fast table speed v. p represents the position of the constant velocity interval within the variable speed curve. Table speed v ^p _stage For example, it is preferable to set the speed change to be possible in units of the tracking distance L. However, the present invention is not limited thereto. Or may change at a speed during tracking. In this case, the constant velocity section is set smaller than the tracking distance L.

In the case of using the XY table 105 at a variable speed, since the speed varies for each section, the cycle time variation is tracked. Therefore, in the case of using the XY table 105 at a variable speed, as shown in the formula (7-1), in the path of the functions σn, m, different from the case of a constant speed, each tracking cycle time t from p=1 to p= (m-n) ^p _trk-cycle Multiplied by 4 lambda.

The effective temperature T in embodiment 2 is calculated in the same manner as in embodiment 1 except for the heat expansion function used.

As described above, according to embodiment 2, even in the case of performing variable speed drawing, in the multi-beam drawing, the influence of the temperature rise per beam emitted per shot is not accumulated, and the resist heating can be corrected.

In the above embodiments, the case where the size s of the processing grid 39 is made equal to the tracking distance L was described, but the present invention is not limited thereto. The thermal expansion due to heat transfer depends only on the distance (=time for raster scanning) of the grid of interest from the grid size considered as a uniform irradiation dose.

Therefore, as the virtual tracking distance for calculating the effective temperature, the size s of the processing grid 39 can be used. Therefore, a value obtained by dividing the size s of the processing grid 39 by the table speed v can be used as the tracking cycle time of the assumption on the calculation. Therefore, the above-described calculation formula of the thermal expansion function can be directly used.

Therefore, the size s of the processing grid 39 may also be different from the tracking distance L. For example, the size s of the processing grid 39 is preferably set to a value smaller than the tracking distance L. This increases the time resolution of the temperature diffusion and the spatial resolution of the dose distribution in the effective temperature calculation formula, and thus can improve the accuracy of the effective temperature. However, since the smaller the mesh size is, the larger the calculation amount of the effective temperature is, the size s of the processing mesh 39 may be defined as the tracking distance L.

The embodiments are described above with reference to specific examples. However, the present invention is not limited to these specific examples.

In addition, although descriptions of the device configuration, the control method, and the like, which are not directly required in the description of the present invention, are omitted, the device configuration and the control method that are required can be appropriately selected and used. For example, the description of the control unit configuration of the control drawing device 100 is omitted, but the necessary control unit configuration may be appropriately selected and used.

All the multi-charged particle beam drawing apparatuses and multi-charged particle beam drawing methods, which are provided with the elements of the present invention and can be appropriately designed and changed by those skilled in the art, are included in the scope of the present invention.

Industrial applicability

The present invention relates to a multi-charged particle beam drawing apparatus and a multi-charged particle beam drawing method, and can be used for example in a correction method for resist heating generated in multi-beam drawing.

Description of symbols

20: multiple beams; 22: a hole; 24: a control electrode; 25: a through hole; 26: a counter electrode; 28. 36: a pixel; 29: a sub-irradiation region; 30: a drawing area; 32: a strip-shaped region; 34: an irradiation region; 35: a rectangular region; 39: processing the grid; 41: a control circuit; 46: an amplifier; 47: a separate blanking mechanism; 50: a pattern density calculation unit; 52: a dose calculation unit; 53: a dividing section; 54: a dose representative value calculation unit; 56: a tracking cycle time calculation unit; 58: an effective temperature calculation unit; 60: a modulation rate calculation unit; 62: a correction unit; 72: an irradiation time data generation unit; 74: a data processing unit; 79: a transmission control unit; 80: a drawing control unit; 100: a drawing device; 101: a sample; 102: an electronic lens barrel; 103: a drawing chamber; 105: an XY table; 110: a control computer; 112: a memory; 130: a deflection control circuit; 132. 134: a DAC amplifier unit; 136: a lens control circuit; 138: a table control mechanism; 139: a table position measuring device; 140. 142, 144: a storage device; 150: a drawing mechanism; 160: a control system circuit; 200: an electron beam; 201: an electron gun; 202: an illumination lens; 203: forming an aperture array substrate; 204: a blanking aperture array mechanism; 205: a reduction lens; 206: limiting the aperture substrate; 207: an objective lens; 208: a main deflector; 209: a sub deflector; 210: a reflecting mirror; 330: a diaphragm region; 343: and (3) a pad.

Claims

1. A multi-charged particle beam drawing device for irradiating a drawing area on a sample surface with a multi-charged particle beam, comprising:

2. The multi-charged-particle beam profiling apparatus of claim 1 wherein,

the processing region is a region of the same size as the beam array region.

3. The multi-charged-particle beam profiling apparatus of claim 1 wherein,

the drawing mechanism has a movable table on which the sample is placed,

the thermal expansion function defines a case where the table moves at a constant speed in the bar shape in a direction opposite to the 2 nd direction.

4. The multi-charged-particle beam profiling apparatus of claim 1 wherein,

the drawing mechanism has a movable table on which the sample is placed,

the thermal expansion function defines a case where the table is variably moved in the opposite direction to the 2 nd direction.

5. The multi-charged-particle beam profiling apparatus of claim 1 wherein,

the drawing mechanism includes:

a stage on which the sample is placed and which is movable; and

a deflector for performing tracking control for deflecting the plurality of charged particle beams to follow the movement of the stage,

as the size of the mesh region, a tracking distance for performing tracking control is used.

6. The multi-charged-particle beam drawing apparatus according to claim 5, wherein,

the thermal expansion function is defined using a tracking cycle time obtained from the speed of the stage.

7. The multi-charged-particle beam drawing apparatus according to claim 5, wherein,

the tracking distance is k times the size of the inter-beam space on the sample surface, where k is a natural number.

8. The multi-charged-particle beam profiling apparatus of claim 1 wherein,

The size of the grid region is larger than the inter-beam spacing on the sample surface.

9. A multi-charged particle beam drawing method is characterized in that,

10. A readable recording medium having a program recorded thereon, the program being for causing a computer to execute the steps of: